/*
 * MIT License
 *
 * Copyright (c) 2010 - 2021 The OSHI Project Contributors: https://github.com/oshi/oshi/graphs/contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package oshi.driver.linux.proc;

import oshi.annotation.concurrent.ThreadSafe;
import oshi.util.FileUtil;
import oshi.util.platform.linux.ProcPath;

/**
 * Utility to read system uptime from {@code /proc/uptime}
 */
@ThreadSafe
public final class UpTime {

    private UpTime() {
    }

    /**
     * Parses the first value in {@code /proc/uptime} for seconds since boot
     *
     * @return Seconds since boot
     */
    public static double getSystemUptimeSeconds() {
        String uptime = FileUtil.getStringFromFile(ProcPath.UPTIME);
        int spaceIndex = uptime.indexOf(' ');
        try {
            if (spaceIndex < 0) {
                // No space, error
                return 0d;
            } else {
                return Double.parseDouble(uptime.substring(0, spaceIndex));
            }
        } catch (NumberFormatException nfe) {
            return 0d;
        }
    }
}
